The
Atmosphere
of Mars |
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| Mars is
quite similar to the Earth in its rotation rate and
the tilt of its axis, so both the daily and seasonal
changes of the Martian atmosphere are much like the
Earth's. Both the Earth and Mars also have similar
global atmospheric circulation
patterns.
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The atmosphere
of Mars, however, is quite different from
that of Earth. The Martian atmosphere
is composed primarily of carbon dioxide
with small amounts of other gases. The
air is thin and unbreathable and contains
95% carbon dioxide, 3% nitrogen, 1.5%
argon, trace amounts of water, and no
oxygen. (Earth has 78% nitrogen, 21% oxygen,
1% argon, and 0.03% carbon dioxide.)
Atmospheric surface pressure is estimated
at between six and seven millibars, or
about 1/150th that of
the Earth.
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Martian air contains
only about 1/1,000th as
much water as our air! Yet, even this small
amount of water can condense out and form
clouds. Local patches of early morning fog
can form in valleys. Scientists believe
that in the past a denser Martian atmosphere
may have allowed water to flow on the planet.
Physical features closely resemble shorelines,
riverbeds, and islands. This suggests that
great rivers and possibly seas once existed
on Mars. |
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While
the average temperature on Mars is about
-67°F (-55°C), Martian surface temperatures
range widely from as little as -207°F (-133°C)
at the winter pole to almost 80°F (27°C)
on the dayside during summer. Click
here for the daily Martian weather
report! |
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| Mars has seasonal dust storms that
can blow over the entire planet for weeks at a
time. These global dust storms fill the air with
fine red dust, giving the sky the same color as
the ground. |
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In
the summer of 2001, the largest dust storm
on Mars in 25 years was seen. The storm
was so big that amateur astronomers using
modest telescopes could see it from Earth.
The cloud raised the temperature of the
frigid Martian atmosphere by 30 degrees
Celsius. A modest dust storm brewing in
Hellas Basin quickly enveloped the whole
planet.
No one knows exactly
how Martian dust storms grow to such proportions.
"One theory holds that airborne dust
particles absorb sunlight and warm the Martian
atmosphere in their vicinity. Warm pockets
of air rush toward colder regions and generate
winds. Strong winds lift more dust off the
ground, which further heats the atmosphere"
says Phil Christensen a scientist from Arizona
State University. For more information on
this giant dust storm, click
here. To see images of the dust storm,
visit this
site. |
Questions
to think about:
- What types of features might your Mars space suit
need to have?
- Do you think you could grow plants on the Martian
surface? Why?
- What danger do dust storms pose for robotic spacecraft
and future explorers?
- What kinds of protection from dust storms would
be needed at a home base and outside on the surface?
- What kinds of equipment can be damaged by fine
dust?
Next... The
Geology of Mars: Volcanoes (pg. 6 of 13) |
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